Computing devices can provide network connectivity using a number of different wired and wireless technologies. The networks to which devices connect are sometimes provided as a subscription-based service for which a consumer pays. Familiar examples of network services are wireline telephone services, wireless phone voice and data services, Internet services, and television services. While the service plans that network service providers offer vary widely in terms and structure, many service plans are based on providing a limited amount of access to a network resource at a fixed cost. If a user exceeds the usage limit the network service provider usually charges the customer for each additional increment of use. For example, a wireless phone plan may permit a certain number of voice minutes and a certain amount of data be transferred for the customer during a month. When a customer exceeds the usage limit for voice minutes, the network service provider may charge the customer for each minute over the limit. Similar overage charges may be imposed for data transfers once the data usage limit is exceeded.